Turkey will continue to block oil tankers without appropriate insurance letters from its waters and has said it needs time to make checks.
The country's maritime authority on Thursday dismissed pressure from abroad over a growing queue of vessels.
Talks between western and Turkish officials on steps to resolve the queues are continuing, a British Treasury official said.
The G7 group of countries, the EU and Australia have agreed to bar shipping service providers such as insurers from helping to export Russian oil unless it is sold at an enforced low price, or cap, to deprive Moscow of wartime revenue.
Price cap on Russian oil
US Deputy Treasury Secretary Wally Adeyemo told Turkish Deputy Foreign Minister Sedat Onal on Wednesday that the price cap only applies to Russian oil and does not necessitate additional checks on ships passing through Turkish territorial waters.
However, Turkey has had a separate measure in force since the start of the month, which is causing a logjam. It requires vessels to provide proof they have insurance covering the duration of their transit through the Bosphorus Strait or when calling at Turkish ports.
In Ankara, the Directorate General for Maritime Affairs said it was unacceptable to mount pressure Turkey over what it called “routine” insurance checks in its waters.
The Transport Ministry body also said it could remove tankers without proper documents from its waters or require from them a new P&I insurance letter that covers their journey through its territory.
In its tally, Tribeca cited tankers longer than 200 metres waiting north of the Bosphorus and said none had a time set for crossing.
At the Dardanelles strait further south, nine south-bound tankers were waiting to cross, down from 12 a day earlier, the agency said.
Three tankers were scheduled to pass through that strait on Thursday, two en route from Russia's Tuapse to Fujairah and one en route from Tuzla, Turkey, to Sidi Kerir, in Egypt.